The US Environmental Protection Agency (EPA) is in the process of allowing growers to use streptomycin and oxytetracycline as routine treatments, spraying trees several times per year, beginning with the ‘first flush’ of leaves this spring. Growers in the state could end up using as much as 440,000 kilograms of the drugs. Although the compounds, which are both used in human medicine, have been sprayed on other crops in the past and applied in limited amounts to citrus groves, the scale of this application has researchers and public-health advocates alarmed.

“They are doing a huge experiment with limited monitoring,” says Steven Roach, a senior analyst in Iowa City at Keep Antibiotics Working, a coalition of research and advocacy groups that has formally objected to the plan with the EPA.
( read more at Nature )

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AbstractWind-dispersed plants have evolved ingenious ways to lift their seeds1,2. The common dandelion uses a bundle of drag-enhancing bristles (the pappus) that helps to keep their seeds aloft. This passive flight mechanism is highly effective, enabling seed dispersal over formidable distances3,4; however, the physics underpinning pappus-mediated flight remains unresolved. Here we visualized the flow around dandelion seeds, uncovering an extraordinary type of vortex. This vortex is a ring of recirculating fluid, which is detached owing to the flow passing through the pappus. We hypothesized that the circular disk-like geometry and the porosity of the pappus are the key design features that enable the formation of the separated vortex ring. The porosity gradient was surveyed using microfabricated disks, and a disk with a similar porosity was found to be able to recapitulate the flow behaviour of the pappus. The porosity of the dandelion pappus appears to be tuned precisely to stabilize the vortex, while maximizing aerodynamic loading and minimizing material requirements. The discovery of the separated vortex ring provides evidence of the existence of a new class of fluid behaviour around fluid-immersed bodies that may underlie locomotion, weight reduction and particle retention in biological and manmade structures.

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Citrus canker is a disease that affects all citrus species and varieties. It is caused by Xanthomonas citri, a bacterium originally from Asia, where it is endemic in all citrus-producing countries. Although the bacterium can be combated in several ways, none is sufficient to eradicate the disease. Therefore, new chemical or biological methods of protecting citrus groves have to be pursued.

In an article published in Letters in Applied Microbiology, a team led by Daiane Cristina Sass, Lara Durães Sette and Henrique Ferreira, professors in São Paulo State University’s Bioscience Institute (IB-UNESP) in Rio Claro, Brazil, identify 29 fungi with proven action against X. citri. The origin of the fungi is surprising. They were isolated from samples of soil and marine sediment collected in Antarctica. read more…

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Dodder vine is an amazing plant, it is orange rather than green due to its lack of chlorophyl, it can’t make its own food.

Instead the dodder vine hatches in the spring from a seed and very slowly moves in a circle searching the air for beta-myrcene a volatile chemical emitted into the air by tomatoes and other plants. When it picks up the scent of beta-myrcene it grows in the direction of the odor until it finds the plant emitting it.

Once it reaches the plant it tightly winds itself around the plant, sinking roots into the host plant. The roots then suck up the juices in the host plant to feed itself. The host plant will then wilt and die.

Dodder vine also appears to exchange RNA with the host plant. Whether this is a way of exchanging information with the host plant or a way to reprogram it, much the way viruses reprogram our DNA is unknown.

Plants use RNA as a way to send messages through out the plant. When a dodder vine attacks a plant some of the plant’s RNA gets sucked up by the dodder vine. The dodder vine can then read the RNA to better evaluate how to attack the host.

Professor Neelima Sinha and colleagues at the UC Davis Section of Plant Biology studied dodder vines growing on tomato plants in the lab. They found that RNA molecules from the host could be found in the dodder up to a foot (30 cm) from the point where the parasite had plumbed itself into the host.

Plants often use small RNA molecules as messengers between different parts of the plant. In a paper published in Science in 2001, Sinha’s group showed that RNA could travel from a graft into the rest of the plant and affect leaf shape. Plants can also use specific RNAs to fight off viruses. . . [ read more Plant Parasite Wiretaps Host ]

Dodder is a member of the Morning Glory family.

It has very tiny leaves that are more like scales than leaves and tiny white flowers.

It is considered an invasive plant and a threat to the local ecology in Texas.

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Black Swallowtail caterpillar
“We show that exposing tomato plants to some level of caterpillar herbivory will increase resistance for future plants—it’s sort of like a plant vaccine,” says Sergio Rasmann, a biologist at the University of Lausanne in Switzerland.

Rasmann isn’t the only one seeing this effect. In a similar study, Ann Slaughter of the Universite de Neuchatel in Switzerland infected Arabidopsis thaliana plants with a benign strain of the bacteria Pseudomonas syringae (PstavrRpt2). The offspring were more resistant to disease than control groups, which were not infected in the first generation.

How does pest resistance get inherited? Researchers point to epigenetic mechanisms, which regulate gene expression and can be passed from one generation to the next without any changes to DNA sequences. The studies suggest known epigenetic factors like DNA methylation and histone modification mediate these effects, and are among the first to demonstrate siRNAs act as an epigenetic mechanism in plant defense responses.

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The NYTimes is reporting that several tree deaths are being linked to the use of the new herbicide Imprelis.

Imprelis uses pyrimidine carboxylic acid (trade name Aptexor )
A recently approved herbicide called Imprelis, widely used by landscapers because it was thought to be environmentally friendly, has emerged as the leading suspect in the deaths of thousands of Norway spruce, eastern white pine and other trees on lawns and golf courses across the country.

Manufactured by DuPont and approved for sale last October by the federal Environmental Protection Agency, Imprelis is used for killing broadleaf weeds like dandelion and clover and is sold to lawn care professionals only. Reports of dying trees started surfacing around Memorial Day, prompting an inquiry by DuPont scientists.

There have been several reports from both outside and within the state of Michigan of herbicide injury on Norway spruce and white pine following application of the turfgrass herbicide Imprelis (a.i. aminocyclopyrachlor). Damaged trees have symptoms consistent with growth regulator type herbicides. Injury includes curling and twisting of new growth. Pictures and comments of damage observed in Indiana can be viewed at Purdue Extension’s Plant and Pest Diagnostic Laboratory website.

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New Gardens

The bamboo, lots of yaupon and a couple not so healthy pines have been removed. A slew of drought tolerant, bee/butterfly/hummingbird attractors have been planted.

I’m learning more about landscaping. As I wander with the hound on our daily walks I snap photos of cool gardens. You’ll see more of those here and more ways to create beautiful environmentally friendly landscapes using native and or cheap, low footprint plants

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